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Brian Karas

For what you describe, I would say you want a minimum of 50ppf on-target. That's not license-plate reading pixel density, but it gives you a solid idea of vehicle types, colors, and prominent features.

20ft x 50ppft = 1000px, eg: you want a camera with 1000 (or more) horizontal pixels. In reality your gate might be slightly narrower, but you're also not likely to have a direct shot, the camera will be a little off to the side, resulting in some skew.

So, you'll likely want a 720p (1280x720px) or higher-res camera.

Lens selection will vary with resolution. At that range, camera shake can start to become a problem, higher shutter speeds would be recommended, which also means you'll need decent light (more of an issue at night than during the day). Your biggest difficulty might be finding a decent/affordable lens. Depending on the camera and imager size, I think you're going to be around a 130mm lens for this.

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John Honovich

Watch out for low light issues. Long lens will have higher f stop. For instance, the Arecont 4.7 - 84.6 is rated as f/1.6 but at 84.6mm I am sure the f stop is way higher.

Equally importantly, higher resolution, poor performing low light cameras, like an Arecont 5MP are going to make things a lot worse. If you have a low light optimized 1.3 or 2MP camera, you may want to compare against that.

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Seth Thompson

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Patrick Christensen

I had a similar situation in that I had to watch a gate that is open most of the time. The entrance is very well lit so I would not have a issue with low light. I didn't have a close location that provided a direct view of the front of the cars entering the facility. I mounted an Axis Q6035C on the side of a building facing the gate entrance. The stright line distance from the front of the lense was just over 465 feet, but the camera is also up 12 feet. I was told that this would not work its to far. It does no problem!. My problem is that the cars are moving towards the camera, so I have a very short view of the front of the car/truck because of the zoom. If the camera is looking at a gate and the car/truck needs to come to a complete stop then I don't think you should have a problem. This is a expensive solution, but it worked for me.

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